main{
    width: 1100px;
    margin: 50px auto;
}

form{
    float: left;
}

h1{
    margin: 0 0 20px;
    font-size: 1.2rem;
    text-align: left;
}
#table1{
    width: 550px;
}
#table1 td:nth-child(1){
    width: 130px;
}
#table1 td:nth-child(2){
    width: 185px;
}
#table1 td{
    height: 30px;
    font-size: 0.9rem;
}
input[type=text]{
    height: 25px;
    width: 165px;
    background-color: #EFF8FF;
    border: 1px solid gray;
}
select{
    width: 163px;
    background-color: #EFF8FF;
    border: 1px solid gray;
    height: 28px;
    font-size: 1rem;
}
input[type=button]{
    width: 163px;
}

section{
    float: right;
}
h4{
    margin: 0px 0px 20px;
    font-size: 0.95rem;
    text-align: left;
}
#table2{
    border-spacing: 0;
}
#table2 td:nth-child(1){
    width: 100px;
    text-align: center;
}
#table2 td:nth-child(2){
    width: 280px;
    text-align: center;
}
td{
    height: 25px;
    font-size: 0.9rem;
}
#table2 tr:nth-child(1){
    font-weight: bold;
    background-color: #8DD8F8;
}
#table2 tr:nth-child(2){
    background-color: #CCCCCC;
}
#table2 tr:nth-child(3){
    background-color: #66CC00;
}
#table2 tr:nth-child(4){
    background-color: #FFFF00;
}
#table2 tr:nth-child(5){
    background-color: #FF9900;
}

/*被隐藏的结果*/

#result{
    height: 40px;
    border: 1px dotted gray;
    background-color: #FFFFAA;
    font-size: 1rem;
    margin-bottom: 20px;
    display: none;
}
#BMI-value{
    color: green;
    font-weight: bold;
}